Polytetrafluoroethylene aqueous dispersion and its product

a technology of polytetrafluoroethylene and aqueous dispersion, applied in the field of polytetrafluoroethylene, can solve the problems of poor wettability and low permeability of obtained aqueous ptfe emulsion, insufficient physical properties of obtained ptfe, and tendency to be repelled, and achieve excellent wettability and mechanical stability

Active Publication Date: 2010-05-04
ASAHI GLASS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0021]The PTFE aqueous dispersion of the present invention does not substantially contain APFO and is excellent in wettability and mechanical stability. Further, the PTFE product obtained by using the PTFE aqueous dispersion of the present invention does not substantially contain APFO, and it is thus desirable.

Problems solved by technology

However, it has been pointed out that APFO has an accumulation potential in a body of a small animal, and with respect to an aqueous PTFE emulsion formed by an emulsion polymerization method by using APFO, there has been a concern expressed about an adverse effect to ecosystem.
However, by this method, only an aqueous PTFE emulsion having a relatively low concentration is obtained, and there is a problem such that the obtained PTFE has not enough physical property.
However, by this method, the obtained aqueous PTFE emulsion has poor wettability and low permeability when it is attempted to impregnate it into a porous material.
Therefore, it has a problem such that when it is applied on a metal plate for coating, it tends to be repelled.
Further, this aqueous PTFE emulsion has a low mechanical stability, and there is a problem such that when the emulsion is transferred by a pump, coagulates tend to be formed.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

reference example 1

Production Example of CF3CF2OCF(CF3)CF2OCF(CF3)COONH4

[0096]2.58 g of CsF and 13.06 g of tetraglyme were charged into a hastelloy c autoclave having a capacity of 200 mL, followed by degassing, and then, 20.83 g of CF3COF was introduced. Then, the autoclave was cooled to −20° C., and under a hermetically sealed and stirred condition, 57.5 g of hexafluoropropene oxide was introduced over a period of about one hour. The initial pressure showed 0.6 MPa. The reaction was continued for about one hour until the pressure no longer decreased, and then, the autoclave was returned to room temperature to obtain 78.57 g of a reaction crude liquid. This liquid was subjected to a GC analysis, whereby it was found that in addition to the objective product, 49.7% of CF3CF2OCF(CF3)CF2OCF(CF3)COF, 19.1% of CF3CF2OCF(CF3)COF and 12.8% of CF3CF2O(CF(CF3)CF2O)2CF(CF3)COF, were contained.

[0097]The same reaction was carried out by using 32.26 g of CF3COF. Distillation and purification were carried out by ...

reference example 2

Measurement of 1-Octanol / Water Partition Coefficient (LogPOW)

[0099]In accordance with OECD Test Guideline 117, 1-octanol / water partition coefficient (LogPOW) of a fluorinated emulsifier was measured by using HPLC (high performance liquid chromatography).

[0100]Conditions for the measurement were as follows: column: TOSOH ODS-120T column (φ 4.6 mm×250 mm), eluent: acetonitrile / 0.6 mass % of HClO4 solution=1 / 1 (vol / vol %), flow rate: 1.0 m / minute, sample amount: 300 μL, column temperature: 40° C., and detection light: UV 210 nm (WO2005-42593).

[0101]HPLC was carried out on standard substances (heptanoic acid, octanoic acid, nonanoic acid and decanoic acid) having known 1-octanol / water partition coefficients, and a calibration curve was prepared from the respective elution times and octanol / water partition coefficients of the respective standard substances. Based on this calibration curve, a value of partition coefficient (LogPOW) between 1-octanol and water was calculated from the eluti...

example 1

[0105]EEA was used as the fluorinated emulsifier. Into a 100 L stainless steel autoclave equipped with a baffle plate and a stirrer, 36 g of EEA, 555 g of paraffin wax (melting point: 55° C.) and 61.3 liters of deionized water were charged. The air in the autoclave was replaced with nitrogen, and then the pressure was reduced. Then, a TFE monomer was added and the temperature was increased to 62° C. with stirring. In addition, the TFE monomer was injected until the inner pressure was raised to 1.765 MPa, and 26.3 g of disuccinic acid peroxide (concentration: 80 mass %, the rest being water) was dissolved in 1 L of warm water at about 70° C. and was injected into the autoclave.

[0106]About 3 minutes later, the inner pressure of the autoclave decreased to 1.716 MPa, whereupon the TFE monomer was injected to keep the inner pressure at 1.765 MPa and to let the polymerization proceed. EEA was dissolved in warm water, and the total of 53 g as EEA was added dividedly in two steps during the...

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PUM

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Abstract

To provide a polytetrafluoroethylene (PTFE) aqueous dispersion, which does not substantially contain ammonium perfluorooctanoate and is excellent in mechanical stability, wettability, permeability and coating property, and its product.A PTFE aqueous dispersion comprising from 15 to 70 mass % of PTFE fine particles having an average particle size of from 0.1 to 0.5 μm, from 1×10−5 to 0.5 mass %, based on the mass of the PTFE, of a fluorinated emulsifier of the formula (1): XCF2CF2(O)mCF2CF2OCF2COOA, wherein X is a hydrogen atom or a fluorine atom, A is a hydrogen atom, an alkali metal or NH4 and m is an integer of 0 or 1, and from 1 to 20 mass %, based on the mass of the PTFE, of a nonionic surfactant.

Description

TECHNICAL FIELD[0001]The present invention relates to a polytetrafluoroethylene (hereinafter referred to as PTFE) aqueous dispersion and its product.BACKGROUND ART[0002]Heretofore, PTFE formed by an emulsion polymerization method is obtained as an aqueous PTFE emulsion containing PTFE fine particles, by polymerizing tetrafluoroethylene (hereinafter referred to as TFE) in the presence of e.g. an aqueous medium, a polymerization initiator, ammonium perfluorooctanoate (hereinafter referred to as APFO) which is an emulsifier, a stabilizing agent such as paraffin wax (Non-Patent Document 1).[0003]However, it has been pointed out that APFO has an accumulation potential in a body of a small animal, and with respect to an aqueous PTFE emulsion formed by an emulsion polymerization method by using APFO, there has been a concern expressed about an adverse effect to ecosystem. Further, there is the same concern about a PTFE product obtained by using the obtained aqueous PTFE emulsion.[0004]As a...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): C03C25/28C09D5/02C09K23/16C09K23/42C09K23/44
CPCB01F17/0035B01F17/0085C08F14/26C08L27/18C08F2/20C08F2/16C08K5/095C08L71/02C08L2666/22C09K23/007C09K23/017
Inventor HOSHIKAWA, JUNHIGUCHI, SHINYAMATSUOKA, YASUHIKOYAMAGISHI, NOBUYUKI
Owner ASAHI GLASS CO LTD
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